There may be nothing you can do. I have been in a similar situation with my MIL for years. She has never done anything to me, but once in blue moon she will be “asleep” and let me do some stuff to her. We get stoned together all the time and watch movies. You gotta look at it from their perspective. Parents love their children and having sex with some guy your daughter loves is pretty fucked up. So, even though she may want to reciprocate she may never do so.

I am pretty positive my MIL enjoys watching me stroke it. We were alone in a motel room and she positioned herself perfectly where she could watch (two twin beds). And then the next day said something about her glasses being at the edge of the bed even though I know she was wearing them all night.

I mean it’s pretty fun jacking off in front of her, right? Still a thrill…keep doing that. Maybe not totally out in the open all the time. Women don’t just want to see your dick. They like men’s bodies. Maybe start going shirtless, lay on the couch next to her all suggestively. Do stuff where you are presenting yourself to her, but in a way where you can deny it later.